I'm feeling my way here (snd following on from FumbleFingers's comment).
An extraordinary leader whose vision, values, integrity and boundless
curiosity inspires all who follow in his footsteps. (Referred to above
as in possible duplicate question)
This contains a list of separate qualities, which can be counted and considered individually. Missing one out would not make a significant change to the meaning. So, being separate, they should take a plural verb.
The suddenness and completeness of death was with them like a
The point here is that the two qualities must be taken together. Death is both sudden and complete. That's its horror: there is no warning and it's final. You cannot separate the suddenness and the completeness, so they become a joint and inclusive noun. Which needs a singular verb.
And the singular verb fits "a presence".
Does that make sense?